The extended objective of the present proposal is to study the female reproductive system during various phases of the reproductive process, with particular emphasis on the differentiating female gamete and fertilization, using cytochemistry, radioautography, transmission and scanning electron microscopy and freeze fracture and culturing methodologies. The study is an attempt to learn more about the submicroscopic organization, spatial arrangements, and chemical composition of the various regularly occurring cytoplasmic constituents of this highly specialized protoplasm and its specialized plasma membrane, which in most instances is sensitive to hormones. The ultimate goal of this research proposal is the correlation of the submicroscopic features of cells of the mammalian reproductive system with the reproductive process.